Abstract
Simultaneous detection of carbon dioxide (CO2) and oxygen (O2) has attracted considerable interest since CO2 and O2 play key roles in various industrial and domestic applications. In this study, a new approach based on a fluorescence ratiometric referencing method was reported to develop an optical dual sensor where platinum (II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) complex used as the O2-sensitive dye, CdSe/ZnS quantum dots (QDs) combined with phenol red used as the CO2-sensitive dye, and CdSe/ZnS QDs used as the reference dye for the simultaneous detection of O2 and CO2. All the dyes were immobilized in a gas-permeable matrix poly (isobutyl methacrylate) (PolyIBM) and subjected to excitation using a 380 nm LED. The as-obtained distinct fluorescence spectral intensities were alternately exposed to analyte gases to observe changes in the fluorescence intensity. In the presence of O2, the fluorescence intensity of the Pt (II) complex was considerably quenched, while in the presence of CO2, the fluorescence intensity of QDs was increased. The corresponding ratiometric sensitivities of the optical dual sensor for O2 and CO2 were approximately 13 and 144, respectively. In addition, the response and recovery for O2 and CO2 were calculated to be 10 s/35 s and 20 s/60 s, respectively. Thus, a ratiometric optical dual gas sensor for the simultaneous detection of O2 and CO2 was successfully developed. Effects of spurious fluctuations in the intensity of external and excitation sources were suppressed by the ratiometric sensing approach.
Highlights
The simultaneous occurrence of carbon dioxide and oxygen is quite common
We describe an optical dual sensor based on the fluorescence ratiometric referencing technique using a single-layer approach
The dual sensor emCO2 based on the fluorescence ratiometric referencing method
Summary
The simultaneous occurrence of carbon dioxide and oxygen is quite common. Processes like photosynthesis, fermentation, respiration, etc. involve the evolution and consumption of both gases at the same time. An additional reference signal exhibited by another fluorophore is available in the designed sensor The sensitivities of such a sensor are calculated as the ratio of the fluorescence intensity of the indicator dye to that of the reference dye at the respective analyte concentrations. The dye platinum (II) meso-tetrakis(pentafluorophenyl) porphyrin (PtTFPP) exhibits outstanding optical properties, including a large Stokes shift, excellent photostability, narrow emission bandwidth, and a higher quantum yield, making it highly suitable for the development of a more efficient oxygen sensor Such indicators are doped into a suitable gas-permeable matrix, such as a polymer or sol–gel matrix, for enhancing molecular contact to achieve higher sensitivities. The developed dual sensor in this study can be utilized in environmental air quality monitoring, gas measurements in biological processes in tissues
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